10... f8e8 Keymer immediately makes a mistake, and his position becomes losing. We could say that Caruana's new move is a \"semi-bluff,\" because Black is doing well with accurate play, but not well enough to have a winning position. The bet is: will my opponent find all the best moves even with little time $2 And if that happens, Black's advantage is small, nothing too dramatic. On the other hand, there is the risk that Black will make a mistake and be immediately lost, as happened in the game. Finding this type of move in the analysis and having the courage to use it show the dual quality of Caruana's opening preparation. 11. h4f5 The white knight escapes, and the weaknesses around the black king make the position practically indefensible. 11... f6g4  12. f2f3  12... e4f3 